Currently, in a Diameter credit control (DCC, Diameter Credit Control) protocol, a DCC client, such as a gateway GPRS support node (GGSN, Gateway GPRS Support Node), may send a credit control request (CCR, Credit Control Request) message to a DCC server, such as an online charge system (OCS, Online Charge System), to apply for a granted service unit; the DCC server may feed back a credit control answer (CCA, Credit Control Answer) message to the DCC client to allocate the granted service unit.
The CCA message sent by the DCC server may carry a validity time (VT, Validity Time) used for indicating the validity of the granted service unit, and also used for indicating that the DCC client needs to send a CCR message within the VT again.
In order to reasonably allocate limited network resources and try to avoid network congestion due to applications for the network resources by a large number of users at the same time, an operator may divide into different time periods according to use habits of the users, and arrange different tariffs for the different time periods. Take a wireless Internet access service for example, a period from 18:00 to 23:59 in a day tends to be an online peak, and data traffic in the network is quite large, while data traffic from 0:00 to 17:59 is relatively small, so that the operator may arrange a tariff of “2 yuan/MB” for the period from 18:00 to 23:59, and arrange a tariff of “0.5 yuan/MB” for the period from 0:00 to 17:59, where 0:00 and 18:00 are tariff time changes (TTC, Tariff Time Change).
If the operator arranges a TTC, a CCA message sent to the DCC client by the DCC server may carry the TTC; the DCC client collects statistics on a used service unit before the TTC and a used service unit after the TTC respectively, and reports, through a next CCR message, the used service unit to the DCC server for charging.
However, in the current DCC protocol, a DCC server feeds back a CCA message only after a CCR message sent by a DCC client is received, and each CCA message carries one TTC and a VT, so that if a tariff is switched in a high frequency, for example, there are multiple tariff time changes in a VT, the DCC client is capable of collecting statistics on the used service unit merely according to the TTC carried in the CCA message, and ignores other TTCs in the VT, which therefore may lead to an error in statistical data, and affect the accuracy of charging.